Mandrel and bearing assembly for downhole drilling motor

Abstract

A downhole drilling motor beating assembly includes a tubular mandrel adapted to connect to a rotational power output of downhole motor. The bearing assembly includes a mandrel having: an upper end proximal to the downhole motor, a lower end with a pin connection distal from the motor, and a longitudinal passage through the mandrel from the upper end to the lower end. The assembly further includes at least one circumferential ring projecting radially outward from an other surface of the tubular mandrel. The ring has and upper shoulder and a lower shoulder and a radial surface. A circumferential upper thrust bushing contacts the upper shoulder of the ring and a circumferential lower thrust bushing contacts the lower shoulder of the ring. An upper thrust beating contacts the upper thrust bushing and a lower thrust bearing contacts the lower thrust bushing. A tubular bearing housing includes a longitudinal passage from an upper end of the housing to a lower end of the housing. The passage includes a lower portion with an internal diameter adapted to receive the lower end of the mandrel and an upper portion with a larger internal diameter adapted to receive the lower beating and bushing and the outer radial surface of the circumferential ring projecting from the mandrel and the upper bushing and beating.

1. A downhole drilling motor bearing assembly comprising:
 a unitary tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a male pin connector distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 a circumferential upper thrust bushing contacting the upper shoulder of the ring; 
 a circumferential lower thrust bushing contacting the lower shoulder of the ring; 
 an upper thrust bearing contacting the upper thrust bushing; 
 a lower thrust bearing contacting the lower thrust bushing; and 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the radial surface of the circumferential ring projecting from the mandrel, and said housing adapted to allow the male pin connector of the mandrel to be disposed outside of the lower end of the bearing housing. 
 
   
   
     2. The bearing assembly of  claim 1  wherein the circumferential ring is formed integral with the mandrel. 
   
   
     3. The bearing assembly of  claim 1  wherein the circumferential ring comprises a ring partially received in a circumferential groove on the outer surface of the mandrel. 
   
   
     4. The bearing assembly of  claim 1  wherein the bearing housing includes a shoulder disposed between the upper portion and lower portion of the housing and said shoulder is adapted to contact the lower thrust bearing. 
   
   
     5. The bearing assembly of  claim 1  wherein the circumferential ring is comprised of a first upper ring having an upper shoulder and a second lower ring having a lower shoulder and said first upper ring is adapted to contact the upper bushing and said second lower ring is adapted to contact the lower bushing. 
   
   
     6. The bearing assembly of  claim 1  farther including:
 at least one seal disposed in the lower portion of the bearing housing proximal to the lower end of the mandrel; and 
 a piston sealing assembly disposed proximal to the upper thrust bearing and adapted to prevent drilling mud from entering into the bearing, and said piston assembly adapted to inject lubricant into the bearings. 
 
   
   
     7. The bearing assembly of  claim 1  wherein the circumferential ring comprises a shrink fit ring received on the outer surface of the bearing mandrel. 
   
   
     8. The bearing assembly of  claim 1  wherein the circumferential ring comprises a ring welded onto an outer surface of the bearing mandrel. 
   
   
     9. A downhole drilling motor bearing assembly comprising:
 a tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a pin connection distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 a circumferential upper thrust bushing contacting the upper shoulder of the ring; 
 a circumferential lower thrust bushing contacting the lower shoulder of the ring; and 
 at least one radial bearing comprising a layer of carbide on at least a portion of the lower portion of the bearing housing and a layer of carbide on at least a portion of the lower end of the mandrel, wherein said layers are adapted to contact one another during rotation of the mandrel within the bearing housing. 
 
   
   
     10. The bearing assembly of  claim 9  further including:
 at least one radial bearing comprising a layer of carbide on at least a portion of the upper portion of the bearing housing and a layer of carbide on at least a portion of the upper end of the mandrel, wherein said layers are adapted to contact one another during rotation of the mandrel within the bearing housing. 
 
   
   
     11. A downhole drilling motor bearing assembly comprising:
 a tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a pin connection distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 a circumferential upper thrust bushing contacting the upper shoulder of the ring; 
 a circumferential lower thrust bushing contacting the lower shoulder of the ring; 
 an upper thrust bearing contacting the upper thrust bushing; 
 a lower thrust bearing contacting the lower thrust bushing; and 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the radial surface of the circumferential ring projecting from the mandrel; and 
 a fluid flow diverter disposed proximal to the upper end of the mandrel to divert a portion of the drilling mud along the outer surface of the mandrel and across the thrust bearings. 
 
   
   
     12. A method of assembling a downhole drilling motor comprising the steps of:
 providing a unitary tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a male pin connector distal from the motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 assembling a circumferential upper thrust bushing in contact with the upper shoulder of the ring; 
 assembling a circumferential lower thrust bushing in contact with the lower shoulder of the ring; 
 assembling an upper thrust bearing in contact with the upper thrust bushing; 
 assembling a lower thrust bearing in contact with the lower thrust bushing; 
 providing a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the outer radial surface of the circumferential ring projecting from the mandrel; and 
 inserting the lower end of the mandrel into the upper end of the bearing housing and passing the male pin connector through the longitudinal passage of the bearing housing and out the lower end of the bearing housing. 
 
   
   
     13. A method of assembling a downhole drilling motor comprising the steps of:
 providing a unitary tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a male pin connector distal from the motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 assembling a circumferential upper thrust bushing in contact with the upper shoulder of the ring; 
 assembling a circumferential lower thrust bushing in contact with the lower shoulder of the ring; 
 assembling an upper thrust bearing in contact with the upper thrust bushing; 
 assembling a lower thrust bearing in contact with the lower thrust bushing; 
 providing a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the outer radial surface of the circumferential ring projecting from the mandrel, said passage having a shoulder disposed between the upper portion and lower portion; and 
 inserting the lower end of the mandrel into the upper end of the bearing housing and passing the male pin connector through the longitudinal passage of the bearing housing and out the lower end of the bearing housing until the lower bearing contacts the shoulder of the bearing housing. 
 
   
   
     14. A method of converting from a sealed bearing assembly to a mud lubricated bearing assembly prior to disposing the mud lubricated bearing assembly in a borehole comprising the steps of:
 providing an assembled bearing assembly for a down drilling motor having a tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a pin connection distal from the motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, sand ring have and upper shoulder and a slower shoulder and a surface; 
 a circumferential upper thrust bushing contacting the upper shoulder of the ring; 
 a circumferential lower thrust bushing contacting the lower shoulder of the ring; 
 an upper thrust bearing contacting the upper thrust bushing; 
 a lower thrust bearing contacting the lower thrust bushing; 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the lower bearing and lower bushing and the upper bushing and upper bearing; 
 a drilling fluid flow diverter disposed proximal to the upper end of the mandrel; 
 at least one seal disposed in the lower portion of the bearing housing proximal to the lower end of the mandrel; 
 a piston sealing assembly disposed proximal to the upper thrust bearing and adapted to prevent drilling mud from entering into the bearing and said piston assembly adapted to inject lubricant into the bearings; 
 removing the piston sealing assembly and the at least one seal disposed on the lower portion of the bearing housing; and 
 removing the tubular bearing mandrel and replacing of with a shorter tubular bearing mandrel. 
 
   
   
     15. A downhole drilling motor bearing assembly comprising:
 a unitary tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a male pin connector distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 an upper thrust bearing disposed above the upper shoulder of the ring; 
 a lower thrust bearing disposed above the upper shoulder of the ring; and 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the radial surface of the circumferential ring projecting from the mandrel, and said housing adapted to allow the male pin connector of the mandrel to be disposed outside of the lower end of the bearing housing. 
 
   
   
     16. The bearing assembly of  claim 15  further including:
 a circumferential upper thrust bushing contacting the upper shoulder of the ring; and 
 a circumferential lower thrust bushing contacting the lower shoulder of the ring; 
 wherein the upper thrust bearing contacts the upper thrust bushing and the lower thrust bearing contacts the lower thrust bushing. 
 
   
   
     17. The bearing assembly of  claim 15  wherein the bearing housing includes a shoulder disposed between the upper portion and lower portion of the housing and said shoulder is adapted to contact the lower thrust bearing. 
   
   
     18. The bearing assembly of  claim 15  further including:
 at least one seal disposed in the lower portion of the bearing housing proximal to the lower end of the mandrel; and 
 a piston sealing assembly disposed proximal to the upper thrust bearing and adapted to prevent drilling mud from entering into the bearing, and said piston assembly adapted to inject lubricant into the bearings. 
 
   
   
     19. A downhole drilling motor bearing assembly comprising:
 a tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a pin connection distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the radial surface of the circumferential ring projecting from the mandrel; and 
 at least one radial bearing comprising a layer of carbide on at least a portion of the lower portion of the bearing housing and a layer of carbide on at least a portion of the lower end of the mandrel, wherein said layers are adapted to contact one another during rotation of the mandrel within the bearing housing. 
 
   
   
     20. The bearing assembly of  claim 19  further including:
 at least one radial bearing comprising a layer of carbide on at least a portion of the upper portion of the bearing housing and a layer of carbide on at least a portion of the upper end of the mandrel, wherein said layers are adapted to contact one another during rotation of the mandrel within the bearing housing. 
 
   
   
     21. A downhole drilling motor bearing assembly comprising:
 a tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a pin connection distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 an upper thrust bearing disposed above the upper shoulder of the ring; 
 a lower thrust bearing disposed above the upper shoulder of the ring; 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the radial surface of the circumferential ring projecting from the mandrel; and 
 a fluid flow diverter disposed proximal to the upper end of the mandrel to divert a portion of the drilling mud along the outer surface of the mandrel and across the thrust bearings. 
 
   
   
     22. A downhole drilling motor mandrel catch assembly including:
 a unitary tubular mandrel adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a male pin connector distal from the downhole motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, and 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, said ring having an upper shoulder and a lower shoulder and a radial surface; 
 
 an upper thrust bearing disposed above the upper shoulder of the ring; 
 a lower thrust bearing disposed above the upper shoulder of the ring; and 
 a tubular bearing housing having:
 a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the radial surface of the circumferential ring projecting from the mandrel, and said housing adapted to allow the male pin connector of the mandrel to be disposed outside of the lower end of the bearing housing, and 
 a shoulder disposed between the upper portion and lower portion of the bearing housing and said shoulder being adapted to prevent the mandrel from exiting the longitudinal passage in the bearing housing. 
 
 
   
   
     23. A method of drilling a borehole includes:
 providing an assembled bearing assembly for a down drilling motor having a tubular mandrel with an upper end adapted to connect to a power output of downhole motor, said mandrel having:
 an upper end proximal to the downhole motor power output, 
 a lower end with a pin connection distal from the motor, 
 a longitudinal passage through the mandrel from the upper end to the lower end, 
 
 at least one circumferential ring projecting radially outward from an outer surface of the tubular mandrel, sand ring have and upper shoulder and a slower shoulder and a surface; 
 a circumferential upper thrust bushing contacting the upper shoulder of the ring; 
 a circumferential lower thrust bushing contacting the lower shoulder of the ring; 
 an upper thrust bearing contacting the upper thrust bushing; 
 a lower thrust bearing contacting the lower thrust bushing; 
 a tubular bearing housing having a longitudinal passage from an upper end of the housing to a lower end of the housing, said passage having a lower portion with an internal diameter adapted to receive the lower end of the mandrel and said housing having an upper portion with a larger internal diameter adapted to receive the lower bearing and lower bushing and the upper bushing and upper bearing; 
 a drilling fluid flow diverter disposed proximal to the upper end of the mandrel; 
 at least one seal disposed in the lower portion of the bearing housing proximal to the lower end of the mandrel; 
 a piston sealing assembly disposed proximal to the upper thrust bearing and adapted to prevent drilling mud from entering into the bearing and said piston assembly adapted to inject lubricant into the bearings; 
 connecting a drill string and downhole motor output to an upper end of said tubular mandrel; 
 connecting a drill bit to a lower end of said tubular mandrel; 
 inserting the drill string, downhole motor, bearing assembly and drill bit into a borehole; 
 pumping drilling fluid down the drill string to power the downhole motor; 
 conducting drilling operations to drill a borehole wherein the drilling fluid is expelled through the drill bit and the sealed thrust bearings are lubricated by the injected lubricant of the piston sealing assembly; 
 continuing drilling operations after piston sealing assembly fails and allows mud to enter the bearing assembly, wherein the drilling mud that enters the bearing assembly lubricates the bearing assembly sufficiently to continue drilling operations.